1. Field of the Invention
This invention relates to crank-type actuators for controlling a translating locking bar for drawers in furniture systems and, more particularly, to structure for preventing jamming of the crank.
2. Background Art
One type of drawer locking system is disclosed in my U.S. Pat. No. 4,609,233. That system is designed for use with a piece of furniture having at least two vertically stacked drawers, each of which has a ramp plate defining an entry slot. A vertically reciprocating locking bar has associated lugs and, through a keyed operator/actuator assembly, is selectively positioned to situate the lugs either in a closed, blocking position with the ramp plates, to thereby prohibit opening of the drawers, or an open position, wherein the lugs each align with a slot in the ramp plates. In this latter position of the locking bar, opening of one of the drawers causes the ramp plate thereon to deflect the locking bar from its open to its closed position, thereby prohibiting opening of the remaining drawer(s). This arrangement prevents opening of more than one drawer as might cause the piece of furniture to tip.
The locking bar position is controlled by a keyed operator which, through a rotary cable, operates a crank-type actuator that is directly attached to and moves the locking bar. The actuator converts rotary motion of the cable into translatory vertical movement of the locking bar. To accomplish this, the actuator has a slide plate which is guided in a channel attached to a frame in which the drawers are slidably mounted. The slide plate has an L-shaped slot with intersecting horizontal and vertical legs. The crank, which is driven by the cable, is journalled for rotation in the channel about an axis and has an eccentric pin which is guided in the L-shaped slot. Rotation of the crank in one direction, with the pin in the horizontal slot leg, causes the pin to drive the slide plate upwardly into the locked position. Opposite rotation of the crank causes the pin to drive the slide plate downwardly into its unlocked position. With the slide plate in its unlocked position, the pin resides at the junction of the horizontal and vertical legs. Thereupon, withdrawal of one of the drawers forces the locking plate and thereby the slide plate upwardly so that the pin resides at the bottom of the vertical leg. Closing of the open drawer slides the locking bar vertically upwardly to its unlocked position so that any drawer can thereafter be pulled out.
While the above system has proven to be very effective, under normal operating conditions, there has been one drawback. The furniture may be jolted, as upon being dropped during shipping or handling, and the locking bar as a result may shift from its open to its closed position with all of the drawers closed. The crank then becomes jammed with the pin residing in the bottom of the vertical leg. This condition is remedied by gaining access to the locking bar and manually shifting it to its unlocked position. This is an inconvenience that may also necessitate expensive service calls.